Conventionally, electric wires are widely used for transferring electric energy. Among these wires, a small-sized wire called a lead wire is frequently used in electric and electronic equipment and the like for transferring weak electric power or electric signals. A general lead wire includes a conductor arranged in its central portion, the conductor having a circular cross section and formed of a single annealed copper wire or a plurality of annealed copper wires bundled together. In the electric wire of this type, the conductor is covered with a tubular covering material formed of a polymer having excellent electrical insulation.
For medical and other applications, use of a lead wire having a conductor formed of carbon fibers has been studied (see Patent Literatures 1 and 2 below).